The overall goal of Project 1 is to determine the molecular mechanisms involved in brain reorganization governed by prenatal availability of choline or folic acid and by apolipoprotein E (apoE) genotype. We have found that the availability of choline during the second half of gestation in rats causes biochemical, structural and electrophysiologic changes in brain as well as profound behavioral modifications.. In general, young adult and aged rats supplemented prenatally with choline and improved performance relative to control and prenatally-deficient animals in tasks measuring memory and attention. In contrast,, prenatally deficient animals were impaired in attentional tasks measuring memory and attention. In contrast, prenatally deficient animals were impaired in attentional tasks but somewhat improved in memory tasks. Studies performed to data indicated that prenatal availability of choline may affect the development of multiple synaptic signaling pathways in brain. Specifically prenatal choline availability modifies hippocampal long-term potential,.acetylcholine (ACh) turnover, phospholipase D activity, and indices of nerve growth factor signaling. We will determine the effects of prenatal choline availability and folate availability on signal transduction systems in brain during development, adulthood and aging. Studies performed to date show that prenatal availability of choline alters the patterns of mitosis and apoptosis in developing brain as well as patterns of expression of several proteins. These data are consistent with our hypothesis that prenatal availability of essential nutrients causes multiple changes in brain organization. We propose to determine the developmental patterns of expression of brain genes using hybridization to high density oligonucleotide arrays and reverse Northern analysis followed by in situ hybridization assays of thus identified genes. The metabolism of folate and choline are highly interrelated; therefore the effects of folate availability on ACh turnover in brain will be examined. Within the brain, choline may be redistribut4ed between cells by a mechanism involving apolipoprotein A-mediated transport of a choline- containing lipid. phosphatidylcholine (PC). We will determine if brain ACh turnover is altered in ApoE-/- mice. We will investigate the possibility that dietary choline will modify ACh turnover in folate deficient and ApoE-/- animals. In addition we propose to determine if apoE-containing lipoproteins can supply PC to cholinergic neurons using a cull culture model.